The pancreas, insulin and diabetes
- Key points
- Insulin and the pancreas
- Insulin, food and energy
- What is diabetes?
- What causes type 1 diabetes?
- What are the symptoms and signs of diabetes?
- How is diabetes diagnosed?
- Can the pancreas recover?
- How common is diabetes?
- What are the risks for other family members?
- Common questions and answers
|
Key Points |
|
Insulin and the pancreas
Insulin is a hormone produced by special cells (called beta cells) in the pancreas. Hormones are chemical messengers that circulate in the blood- sending messages to other parts of the body. The pancreas is located deep in the upper part of the abdomen- behind the stomach (see the illustration). The pancreas has two main functions:
- Digestion of foodthe pancreas produces enzymes that are released into the bowel after a meal to help digestion of food. Diabetes does not affect this part of the pancreas.
- Production of hormonesthere are groups of cells in the pancreas called islets of Langerhans that produce a variety of hormonesinsulin and glucagon are two important ones. These hormones help to regulate energy in the body. In diabetes- the cells that make insulin (the beta cells) are damaged.
Insulin, food and energy
After we eat- the food is digested in the stomach and the upper part of the bowel. The nutrients from the digested food are taken into the bloodstream. The carbohydrates (sugars and starches) in our food are broken down into glucose which enters the bloodstream. This glucose is used immediately for energy or can be stored in the liver or muscle as a substance called glycogen. Glucose can be released from glycogen when needed and glucose output from the liver contributes to blood glucose levels- as well as food that has just been eaten.
Position of the pancreas in the body
We need insulin to help the body use glucose from the bloodstream for energy. Glucose is the major energy source for the cells of the body- but normally glucose can only pass from the bloodstream into cells if insulin is present. If there is no insulin- blood glucose levels will be high but none of the glucose can be used for energy since it cannot enter the cells.
Ketones are other substances which the body can sometimes use for energy if it cannot use glucose. In people without diabetes- ketones start to be produced from fat as an alternative energy source when supplies of glucose are becoming low- such as during fasting or illness. This can also be the case in people with diabetes- but more commonly in diabetes- production of ketones means there is a lack of insulin and the glucose that is present in the blood is unable to be used for energy. You will learn more about ketones in section 10 ‘Sick days’.
How insulin helps the body use glucose from the bloodstream for energy
What is diabetes?
DIABETES mellitus (often just called diabetes) occurs when the body cannot produce enough insulin- or when the insulin that the body makes does not work properly. The name comes from the ancient Greek word diabetes meaning siphon or running through (referring to the passing of large amounts of urine) and mellitus meaning honey—like (referring to the sweetness of the urine due to excess sugar as identified by ancient physicians).
There are two main types of diabetes- and some other rare forms:
- Type 1 or insulin—dependent diabetes mellitus (IDDM) is the type that is almost always found in children and adolescents and occurs because the pancreas loses the ability to make insulin. People with type 1 diabetes need insulin treatment to stay alive. Most of this site is about type 1 diabetes.
- Type 2 or non—insulin—dependent diabetes mellitus (NIDDM) usually affects older people and is often associated with being overweight. These people make some insulin- but the insulin does not work well. Type 2 diabetes can often be controlled by changes to diet and weight control- but may need tablets or sometimes insulin injections.Type 2 diabetes is covered in more detail in section 13 "Type 2 diabetes". It is starting to be seen more in younger people.
- Other types of diabetes rarely occur and are usually associated with other conditions that damage the pancreas. These types of diabetes are usually called secondary diabetes.
What causes type 1 diabetes?
THE cause of diabetes is complex and not fully understood. We do know that diabetes occurs because of a combination of a person’s genes and some things in the environment. If a person who has inherited the tendency to develop diabetes comes in contact with a trigger in the environment- then diabetes may develop. The triggers are poorly understood- but may be common things in our environment which are harmless to most people; for example- common viruses or things that we eat. The trigger may be different for different people.
If diabetes is triggered- the body’s immune system- which normally protects us from infections- begins to attack the beta cells of the pancreas. The immune system seems to have been tricked into thinking that the beta cells are foreign to the body and starts to destroy them- causing a decrease in insulin production. It can take from a few weeks to a few years for all of the beta cells to be destroyed.
The pancreas has many beta cells to spare- so symptoms of diabetes do not occur until more than 90 per cent of the cells have been destroyed. This means it is difficult to tell if someone is developing diabetes (ie- it’s difficult to tell they’re in the prediabetes phase) until the symptoms of diabetes occur. Special blood tests can detect people in the prediabetes phase but at this stage are only useful for research- since no treatment is yet proven to stop diabetes developing.
It is important to remember the following points:
- Diabetes cannot be caught from another person. It is not contagious.
- Type 1 diabetes is not caused by eating too much sugar or any other foods.
- There is nothing you could have done to prevent your child from getting diabetes. It was something that was going to happen anyway.
- Your child cannot grow out of type 1 diabetes. It does not change to type 2 diabetes as they get older.
What are the symptoms and signs of diabetes?
WHEN diabetes develops- glucose levels rise above normal- often as much as five to ten times normal. Excess glucose spills over into the urine- drawing water with it and causing excessive passing of urine and dehydration. Thirst increases as the body tries to compensate- and the young person may drink large amounts of fluid.
Weight loss is common over weeks to months- since the body cannot use glucose for energy and instead starts to break down fat and muscle. Excessive tiredness and mood changes are common because the child is feeling unwell. Breakdown of fat causes chemicals called ketones to accumulate in the blood- and this can cause abdominal (tummy) pains- nausea and vomiting.
The common symptoms and signs of diabetes are:
|
Other possible symptoms include:
- oral or vaginal thrush or skin infections (germs thrive in a high glucose environment)
- abdominal (tummy) pains
- decreased school performance because of feeling unwell
- excessive hunger
Ketoacidosis
Where the diabetes comes on quickly- or is found late- the child can become very ill. Glucose and ketone levels become very high in the blood- and there is severe dehydration and loss of salts from the body. Coma may occur. This is called diabetic ketoacidosis.
The onset of diabetes can be especially rapid in babies and young infants- and symptoms and signs may be less easily noticed than in older children.
How is diabetes diagnosed?
IN most cases the diagnosis of diabetes is simple. If symptoms suggest diabetes- your doctor will perform a urine test (for glucose and ketones) and a blood test (for a blood glucose level). Normally the urine contains no glucose; glucose only spills over into the urine when the blood glucose is high- so glucose in the urine is highly suggestive of diabetes. A high blood glucose level is then used to confirm the diagnosis. In most cases no other tests are necessary- but occasionally in doubtful cases a diabetes specialist may recommend a more detailed blood test called a glucose tolerance test.
Can the pancreas recover?
MANY treatments have been tried to stop the damage to beta cells in the pancreas- but at present there is no safe or effective way to do this. This is an active area of research. When insulin treatment is started- the pancreas is able to rest and recover to some degree- but not enough to produce all the insulin the body needs. For a time- the child’s own pancreas may continue to produce up to half or more of the insulin needed by the body- and this period is called the remission phase or honeymoon period. This can be a period where children require quite small doses of insulin. Unfortunately the damaging processes in the pancreas are irreversible and continue. Over a period of time- from a few weeks to many months- the pancreas becomes unable to produce any insulin and all the body’s need for it must be met by injection.
How common is diabetes?
EACH year in our population about 15 to 20 children per 100 000 develop type 1 diabetes (for children aged less than 15 years). Diabetes can come on at any age in children- but around ten to 12 years is most common and it is also quite common around two to three years. It is estimated that there are around 5000—6000 children and adolescents in Australia with type 1 diabetes under 15 years of age. On average- at a high school there will be one student per 500 with diabetes- and in primary schools about one student per 1200.
Our population has an intermediate incidence of type 1 diabetes compared to other countries around the world. Incidence is low in Asian populations (a quarter to one half of our incidence) and highest in Finland (approximately double our incidence). The differences probably relate largely to genetic factors.
What are the risks for other family members?
WHILE inheritance of genes contributes to the risk of diabetes- the risk for other family members developing diabetes is still low. The long—term risk of a brother or sister developing diabetes (assuming no type 1 diabetes in any other close family members) is about 3—6 per cent. If there is more than one person with type 1 diabetes in the immediate family- risks for other children will be higher. For parents with diabetes- if the mother has diabetes the risk for a child is 1—2 per cent- but if the father has diabetes the risk is 4—6 per cent.
In an identical twin the risk is much higherat least 35 per cent. Remember that diabetes is not contagiousthe risk relates to genetic factors